This invention relates to a course guidance system having a rough-and-dense locus display mechanism. In a course guidance system which includes an electronic display disposed, for example, at the driver's seat of a car, a map adapted to the display surface of the display and a direction sensor and a speed sensor mounted in the car for deriving the present position of the car and plotting it on the display so as to guide the course the car is driven in association with the map, the present invention relates to a course guidance system for a car having a rough-and-dense locus display mechanism in which, when the driving locus of the car consisting of a plotted line displayed on the display, for example, is moved linearly or rotated, the plotted points of the driving locus are jump-displayed at predetermined intervals so that the display of the plotted line progressively changes from rough to dense and the driving locus can be displayed visibly at a far higher speed than when it is displayed dense from the beginning.
As micro-computers have become readily available in recent years, driving navigators for cars, for example, have been developed. As one of the navigators of this kind, a course driving system has been developed which includes a direction sensor and a speed sensor mounted in the car for deriving the position of the car and a CRT display for plotting the driving locus and in which a map is associated with the display so that the plot of the driving locus extends along the roads on the map.
When this system is used, linear motion or rotation of the locus display is effected through a keyboard operation in order to make the driving locus on the display accurately correspond to the map. In this case, the driving locus is expressed as a continuous line of an extremely great number of points representating transient driving positions from the past to a given moment in accordance with the distance the car was driven detected by the speed sensor. If this plotted line is continuously processed one dot at a time and displayed, a relatively long period of time is required before the entire locus is displayed. If linear motion or rotation of the locus is effected, a long time is necessary in order to see to what extent the locus is changed, resulting in the drawback that correspondence to the map can not be made quickly. Especially when linear motion or the like of the driving locus is made while the car is driven at a high speed, high speed processing is essential.
The present invention is primarily directed to meet this requirement. The present invention will now be described in detail with reference to the accompanying drawings.